Conventional lighting such as incandescent lamps and fluorescent lamps are relatively inefficient. A significant proportion of the electrical power supplied to conventional lighting fixtures is converted into heat instead of light.
Solid-state light sources such as light-emitting diodes (‘LEDs’) can convert electrical energy into light much more efficiently than incandescent or fluorescent bulbs. LEDs having high power and reliability suitable for use in architectural lighting applications are now available.
There is a general desire for light sources that can be dimmed. Many buildings are wired with AC phase-cut dimmers. Such dimmers are capable of dimming incandescent lamps by reducing the power delivered to the lamps. This is done by cutting off a portion of the AC waveform. Most solid-state lighting circuits are not well suited to being controlled by AC phase cut dimmers. While solid-state lighting systems can be designed to work with different control technologies, there is a very large installed base of AC phase cut dimmers. There is a need for more-efficient solid-state lighting systems that can be dimmed by AC phase-cut dimmers.
Solid state lighting systems have the advantage of improved energy efficiency. Further, a solid-state lighting system may be designed to provide control over power factor.
Solid state lighting systems have the additional advantage that the light emitters are powered at low voltages. Low voltage electrical power is safe. Low-voltage components do not require the same safety certifications that are required for lighting systems that use higher voltages such as the 110 volts or higher AC voltages typically used in North America to power incandescent and fluorescent lights. There remains a need for solid-state lighting systems that can be powered by higher AC voltages (such as household AC current) while ensuring the safety of users.